A biomedical electrode is a flexible, electrically conductive sheet of material having a sticky surface which is placed in contact with the skin of a patient for transferring electromedical signals, such as cardiovascular signals, to electrocardiographic equipment or for stimulating the patient by applying electrical current through the electrode to the patient. Whether they are for stimulation or for electrocardiographic readings, i.e., monitoring, the flexible electrodes (referred to as external electrodes) are placed at selected locations on the skin of the patient and are held in place by adhesive. They include a conductive gel which provides the required electrical conductivity for transferring signals to or from the body through the electrode. These signals to or from the body through the electrode. These electrodes include a lateral extension (tab) on one side or a metal terminal, i.e., a steel snap member to which a wire can be connected.
The present invention is concerned with the provision of an improved connector or clasp for making electrical contact with such monitoring or stimulating electrodes by securely gripping the tab portion of the electrode or snap, as the case may be, as well as to provide an electrical connection with several sizes of male pin-type cable connectors that are now in common use for transferring electromedical signals.
Clasps previously available have been complicated in construction, subject to malfunction, and sometimes expensive to assemble. In addition, they did not always provide a strong gripping force or, in some cases, tended to be loose at the point of articulation so that the jaws of the clasp could wobble from side to side. Another problem was the requirement for using a threaded coupler or soldered connection between the electrical lead wire and the clasp. Another problem with many previously available clasps is that the gripping portion, i.e., the jaw, has only one conductive surface, causing an interruption in transfer of electrical signals when accidentally attached upside-down to the electrode tab which is only conductive on one side, usually its lower side.
A general objective of the invention is to provide an improved clasp that is especially well suited for use with diagnostic electrodes and is adapted to connect to both tab-type electrodes and to snap-type electrodes.
A further object is to provide a clasp that can be easily opened with moderate finger pressure but yet provides a strong, secure closing action for reliably gripping the electrode.
Another object is to provide a clasp that is more reliable in operation, less subject to damage or malfunction, and which can be easily and quickly assembled.
A further object is to employ a single spring that supports a gripping lever which closes the jaws and also provides a receptacle at the other end for pin-type connectors of various sizes that are now in commercial use. More specifically, it is an object to find a way of using a spring which is of a one-piece, i.e. unitary, construction that will eliminate the risk associated with a soldered joint formerly used, which is subject to breakage, so as to thereby guarantee an uninterrupted transfer of electrical signals from the gripping jaws to the receptacle end of the clasp to which is attached the pin connector at the end of a lead wire.
It is another object to provide a spring that is wider wire springs than presently used in the trade, so as to achieve a sturdier construction and larger contact surface area for maximum conductivity at the gripping end of the clasp.
Yet another object is to provide a simply constructed and reliable clasp having an articulated clasp lever (for opening and closing the jaws of the clasp) which is supported upon the base of the clasp by a one-piece spring that provides the spring action for closing the jaws of the clasp as well as for securing a pin connector to the clasp.
Another object is to find a way of preventing the clasp from accidentally contacting the sticky hydrogel portion of the flexible electrode which, when it occurs, will cause what is known as "base-line wander", a completely unacceptable condition that distorts the electrical signal received.
Another object is to provide a retaining hook or prong which will pierce the electrode tab yet cause less damage to the tab and, in addition, is inherently easier to remove from the tab when the jaws are open.
Yet another object is to find a way of preventing lead wires from becoming entangled between the gripping end portions of the clasp levers.
Still a further object is to provide resilient or yieldable gripping elements that slidably engage and yieldably contact opposing surfaces of a pin connector for securely gripping the pin to provide a reliable electrical connection therewith.
These and other more detailed and specific objects of the present invention will be apparent in view of the following description setting forth by way of example but a few of the various forms of the invention that will be apparent to those skilled in the art once the principles described herein are understood.